Telecommunication and remote sensing data exchanged between Earth and space has increased dramatically in recent years. Radio frequencies, the medium used for several decades has shown to reach its capacity. Free space optical communications, achieved with laser transmitter devices, is an alternative with better transmission rate and increased security. However, a major drawback of this technology is that laser signal cannot cross through thick clouds, which imply to set up a network of optical ground stations with handover management strategies based on Cloud Optical Depth (COD) observation and Cloud Motion forecasts. Ground-based long-wave infrared observations from a sky imager can be used to estimate COD. However, as a low thin cloud may have similar thermal signature than a high thick cloud, additional Cloud Base Height (CBH) measurement is needed to retrieve accurate COD in any weather situation [1]. The CCSDS currently recommends to use a ceilometer for this purpose [2]. Here, we explore an alternative approach, retrieving CBH directly from a pair of thermal sky imagers and stereoscopic methods. Our CBH retrievals have been compared with the measurement of a reference ceilometer. The results showed a good agreement for a continuous period of acquisition over several days, with a Root Mean Squared Error of 15%. In addition, stereoscopy offers a wider field of view and thus, may increase the forecasting horizon and accuracy, compared to a sky imager+ceilometer configuration [3] [4] [5]. We believe this approach is promising for the cloud monitoring of Optical Ground Stations and should be further investigated.
We describe the contribution of thermal infrared ground-based cameras in the short term Global Horizontal Irradiance (GHI) forecasting. This contribution is compared to the one of visible cameras, the most widespread technology currently used for this application. Accurate forecasts at short term horizons (5 to 30 minutes) under various and changing weather conditions represent an essential data for various applications such as optical availability and solar plant control procedures. The work presented in this paper first draw up an overview of the two cameras used in the following comparative study. The segmentation methods chosen for each of the camera and the protocol are subsequently described. Finally, the results of the study are presented and discussed. Thanks to the new opportunities it offers in terms of feature extraction and its capacities to overcome visible limitations, the thermal infrared camera shows a sizeable improvement in this comparative study.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.